The Mec III doesn't come with a hook as standard, but it's possible to get an addition to it which is the bottom ear with a hook engineered into it. From memory that addition is around £80.
The Mec Free position is the one that comes with a hook as standard.
With butts in general, as long as they don't come loose it's all about fit and how it fits to you, and if it has enough adjustment to do that. Remember the better you get a hook fitting for your position, the less flexible it will be in fitting others. So it's a case of working out what your current one lacks and look for what there is out there. Mec also do the IV which is narrow and consequently finding favour. There's G&E as well, anschutz do some new ones.